Centrifugally operated engine speed governor



R. C. CROSS May 22, 1945.

CE`iTRIFUGALLY-OPERATED ENGINE SPEED GOVERNOR Filed June 12, 1943/A/wi/vTo/J me/VD C. C8055 Patented May 22, 1945 CENTRIFUGALLY OPERATEDENGINE SPEED GOVERNOR Roland Claude Cross, Bath, England ApplicationJune 12, 1943, Serial No. 490,660 In Great Britain November 11, 1941 2Claims.

This invention relates to centrifugal governors of the kind comprisingone or more centrifugal weights each of which is carried at the free endof a strip of springy material (e. g. spring steel) so that movement ofthe weight, due to centrifugal force, flexes said strip ofspringy*material. Governors of this kind are normally highly sensitiveand efficient primarily due to the fact that the weight acted upon bycentrifugal force is almost entirely free of friction, and in theirapplication to engine control according to the invention they respond tovery small changes in angular velocity around a critical revolutionrate.

Heretofore, governors of the foregoing kind have been proposed forvarious purposes wherein weights at the ends of flexible strips ofspringy material are caused by centrifugal force, at a predeterminedspeed of the governor, to contact frictionally a member held stationaryrelatively to the rotatable governor to prevent the governor exceedingsaid speed.

According to the present invention such a governor is utilised forgoverning the speed of an engine, and accordingly a governor of the kindset forth driven by the engine is combined with a drum adapted toreceive a turning movement according to the speed of the governor byfrictional contact between the governor weights and the drum, said drumbeing coupled to operate the engine throttle.

The drum may surround the governor weights so as to be frictionallycontacted thereby when the engine exceeds a predetermined high speed.There may be a second drum adapted to be frictionally contacted andmoved by the weights as they move inwardly when the engine slows down toa predetermined low speed.

In order that the invention may be clearly understood and readilycarried into effect reference will now be made to the accompanyingdrawing which illustrates an embodiment of the invention by way ofexample. In the drawing:

Figures l and 2 comprise a sectional side elevation and an end View ofthe governor.

Referring to the drawing the governor comprises a driving spindle Irotated by the engine the speed of which is to be controlled, To thespindle I is secured a rotatable body member 2 carrying one end of eachof two strips 3 of spring steel. The free end of each spring steel strip3 ras secured thereto a centrifugal weight 4 adapted to be thrownoutwardly by centrifugal force when the body member 2 is rotated by thedriving spindle I at a predetermined speed. The weights 4 are thrownoutwardly when the engine exceeds a predetermined high speed to such anextent that they frictionally contact the inside surface of a drum 5mounted to rotate freely on the driving spindle I, this drum 5 beingconnected directly by an arm 6 and a link I or through gearing (notshown) with the engine throttle so as to close the latter. The arm 6 orthe gears are only subject to partial rotation. When gears are used oneof them is fitted with a pin for receiving a connection tted to thethrottle. The throttle may be spring loaded so as to open automaticallywhen the speed of the driving shaft diminishes and the centrifugalweights 4 cease to make contact withfthe drum 5.

By mounting the weights 4 on strips 3 of spring steel there is, exceptfor the very slight hysteresis brought about by the deflection of thespring steel strips (and this can be considered absolutely negligible)no friction whatever relative to the weight moving outwards againstspring pressure as it is acted upon by centrifugal force.

The strips 3 of spring steel are preferably loaded by coiled tensionsprings 8 which are adjustable to regulate the outward movement of theweights 4.

It will be seen that this arrangement provides an extremely simple servodevice, which, at the same time, is not so positive that the apparatuscould become wrecked if anything jammed up outside of the governor.

Nevertheless, very considerable torque for operating the throttle couldbe achieved from this system by utilising (in the case of gearing) agear reduction driven by the rotating drum 5. It will be seen that witha gear of, say, something between /1 and 100/ 1, a very slight torquewould be necessary at the drum to give a strong twisting movement at thethrottle. This would enable a very strong counteracting spring to beused for opening the throttle. y Further, when the friction between thedrum 5 and the weight-s Il ceases and the spring loading the throttlestarts to work the other way, the gears would act as a dashpot, and theaction would be steady and not jerky. Sudden opening and closing of athrottle is not conducive to the best results.

If necessary, where extreme sensitivity and quick action are requiredwith light loads, the gearing mentioned in the foregoing embodiment canbe omitted and the drum made to act direct through the arm 6 and lever'I upon the throttle against spring pressure. In such an arrangementvigorous an action to incorporate some form of a dashpot ortheequivalent of which there are According to the illustrated form ofthe invention a smaller drum 9 is provided in spaced relationship insidethe iirst mentioned drum 5 so that the centrifugal weights 4, whenmoving inwardly as the engine slows down to a predetermined low speed,frictionally contact this second mentioned drum 9 and the ensuing torqueapplied to this second drum could be used for opening the throttle inplace of the spring arrangement previously referred to. For this purposean arm 6a and lever 1a may be provided which are operatively connectedwith the inner drum 9.

When two drums 5 and 9 are employed as described above the inner drum 9may if desired be used simply as a braking device adapted to hold thethrottle fixed in a desired open position while the weight or weights 4are travelling around the annular space between the drums and touchingneither the inner or outer drums. This state of aiairs would occur whenthe load remained steady for long periods.

In `the case of an overriding hand control for the engine throttle thiscould be used to operate a disconnecting clutch between the engine andthe governor so that either the automatic control or the hand control iseifective.

In all constructions the actual amount of travel outwards by therevolving centrifugal weights however it may be desirable in order toavoid too is very slight as will be seen from the drawing. Where extremesensitivity is required this distance need only be a few thousandths ofan inch.

From the foregoing it is evident that the device will keep the enginevery steady because the weights can touch against the drum or one of thedrums only very lightly if the speed is close to the desired one and thefriction will be only just sufiicient to counteract the spring pressureoperating in the opposite direction.

I claim:

1. A governor comprising a rotatable shaft, flexible arms mounted onsaid shaft for rotation therewith and for inward and outward ilexurerelative thereto, weights carried by said arms, a drum surrounding saidweights and with which said weights are engageable under the action ofcentrifugal force when said shaft is rotated at and above-apredetermined speed, a second drum disposed inwardly of said weights,coil tension springs connecting said arms and eiective to ilex theminwardly to cause engagement of said weights with said second-mentioneddrum when said shaft is rotated at less than said predetermined speed,and adustable means for varying the tension of said springs.

2. A governor comprising a rotatable shaft. ilexible arms mounted onsaid shaft for rotation therewith and for inward and outward iiexurerelative thereto, weightscarried by said arms, a drum surrounding saidweights and with which said weights are engageable under the action ofcentrifugal force when said shaft is rotated at and above apredetermined speed, a second drum disposed inwardly of said weights,yieldable means separate from said arms effective to flex said armsinwardly to cause engagement of saidweights with said second-mentioneddrum when said shaft is rotated at less than said predetermined speed,and means for adjusting said yieldable means to vary the force exertedby the same to flex said arms inwardly.

ROLAND CLAUDE CROSS.

